Gas heaters that heat a radiating body with combustion heat produced by the burning of fuel gas and that heat industrial materials and food and the like with radiating heat from the radiation surface of a radiating body are widely gaining popularity.
Also, technology has been proposed that increases the thermal efficiency by preheating the fuel gas prior to combustion with the heat of exhaust gas (For example, Patent Document 1). In Patent Document 1, a constitution is disclosed that is provided with a combustion chamber that comes into contact with the outer wall that is disposed around the outer circumference of the main body, a lead-in portion that guides fuel gas from the center of the main body to the combustion chamber, and a lead-out portion that concentrates post-combustion exhaust gas at the center of the main body and guides it to outside the body, with the lead-in portion and the lead-out portion made adjacent to each other by having a partitioning plate serve as a boundary.